Motor-control system.



R. E. HELLMUND.

MOTOR CONTROL SYSTEM.

APPLICATION FILED JUNE l 1. 1915.

Patented Nov. 19, 1918.

5 SHEETS-SHEET l Swift/rs INVENTOR mJy/f 5 y/md WITNESSES A BY lATfoRNl-:Y'

R. E. HELLMUND.

MOTOR CONTROL SYSTEM.

APPLICATION FILED IuNE II. I9I5.

Patented Nov. 19, -1918.

5 SHEETS--SHEET 2.

WITNESSES: Za/MM ATTORNEY R. E. HELLMUND. MOTOR CONTHUL SYSTEM.

APPLICATION FILED IuNE IIL 1915.

Patented Nov. 19, 1918.-

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MOTOR CONTROL SYSTEM.

APPLICATION f|LED1uNE1|.|915.

[im 2J Vl ATTORNEY Patented Nov. 19, 1918..

R. E. HELLIVIUND.

MOTOR CONTROL SYSTEM.- APPLlcATloN FILED JUNE 1\. 19\5.

Patented Nov. 19, 1918.

5 SHEETS-SHEET 5.

Y INVENTOR Pvda/ .E 'HH/muffa WITNES'SES:

ATTORNEY tive devices.

STATES' PATENT OFFICE. f

RUDOLF E. HELLMUND, 0F PITTSBURGH, PENNSYLVANIA, ASSIG-NOR TO WESTING- HOUSEv ELECTRIC AND MANUFACTURING COMPANY, A-CORPORATION 0F PENN- SYLVANIA.

MOTOR-CONTRUL SYSTEM.4

Spcification of Letters Patent.

Application filed June 11, 1915. Seria1No.33,482.

To all 'whom t may concern:

Be it known that I, RUDOLF E. HELL- MUND, a subject of the-Emperor of Germany, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful lmprovementv in Motor-Control Systems, of which the following is a speciication.

My invention relates to systems of control for single-phase alternating-current motors of the compensated doubly-fed type, and it has for its object to provide means whereby a large number of evenly graded accelerating steps may be obtained by, the use of com? paratively few control switches and preven- In the accompanying drawing, Figures 1, 3, l2, 1,4, 16 and 18 are diagrammatic views of singlephase motors, together with their attendant supply and control circuits, illustrating olierent forms of my invention; Figs. 2, 4, 13, 15, 17 and 19 are sequence charts illustrating the method of switchA operation `in the attendant control systems; Figs. 5 to`11, inclusive, are simplified diagrammatic views showing in detail the method of switch operation lemployed in connection with the circuit oi Fig. 1; Figs. 20 to 27, inclusive, are similar views, explanatory orP Fig. 18; and Figs. 5a, 11, 12,

views illustrating the distinctive features of .the accompanying control systems.

In the operation of single-phase alternating-current railway systems, it has been found highly desirable to employ motors of the commutator type because of the flexibility of speed control attendant upon appara tus of this character. Various systems have been developed whereby a motor of the character describedV may be accelerated in a smooth and gradual manner and, at the same time, the commutating ield strength may be adjusted to such values as to minimize sparking and to eliminate the necessity for auxiliary spark-suppressing devices,

. such, for example as resistance leads to the commutator.

In the design of control systems of the character above specified, it is necessary to employ a considerable number of control switches, each of which entails expense, weightv and complication and it is furthermore necessary to employ several reslstance members for series connection in the motor circuit to reduce the motor current and for eliminating transformer shortfcircuits when changing over from one transformer tap to another.

By my invention, l reduce the number of control switches to a minimum and, furthermore, use the same resistance member or members repeatedly to perform dierent func-tions in the acceleration of a motor of the character described.

Referringl to the form of my invention Vshown in Fig. 1, l have shown a source of alternating current at 20, such, for example, as the secondary winding of'aj railway vehicle transformer. A motor 21 of the compensated commutator type is arranged Jfor energization from the source v2O and comprises an armature 22, a main field winding 23 and a cross field winding 24. Suitable control switches l to 8, inclusive, and resistance members 25, 26 and 27 are employed in accelerating the motor 21 in accordance with the sequence chart of Fig. 2, the proper sequence being maintained by any suitable means, either manual or automatic.

Referring to Fig. 2, it will be seen that, at the outset, switches 1, 2 and 6 are closed, the armature, the main ield winding 23, the cross field winding 24 and the resistance member 25 are all connected in series relation between the tap 1 and the tap 6, and the armature 22 is short circuited through the member 26 for repulsion operation, all as indicated in Fig. 5. ln the accelerating step 2, the switch 4 is closed, eliminating the resistance vmember 25 from the circuit and 'therefore increasing the motor current, as indicated in Fig. 6. rlhe switch 3 is then closed, introducing an intermediate tap for the doubly-fed connection, as shown in Fig. 7, and, immediately thereafter, the'switch 2 is opened, establishing the doubly-fed connection shown in Fig. 8. ln the accelerating positions 5, 6 and 7, the switches 6, 7 and 8 and the resistance member 27 are manipulated to change the motor connection from the tap 6 to the tap 8, thus increasing the voltage applied to the cross field winding 24, as indicated in Fig. 9. The resistance member 25 is now reintroduced and employed as a preventive device in shifting the .intermediate connection of themotor from the tap 3 to the tap 5, as indicated in Patented N0v. 1e, 1918.

25 additional accelerating steps 2 and 12v illusaccelerating steps 8, 9 and 10, andthe resistance member 25 is finally short circuited, as shown in Figs. 10 and 11.

It will be seen from the above explanation that the resistance member 25 is employed both as a series-connected rheostat and as a preventive device in raising the voltage and that its use in both relations is controlled by exceedingly simple connections.l Asmooth and well balanced acceleration is obtained, as is indicated in the last column of the chart of' Fig. 2 wherein the steps indicated by A are pure acceleration steps; those indicated by R are suitable for running; and those indicated by T are merely transition steps and are liever maintained for any appreciable length of time.

Referring t0 the form of my invention` shown in Fig. 3, the general system of connections the same as indicated in Fig. 1 with the addition of a resistance member 28, connected in shunt relation to the member 25 and controlled by a switch 9. As

will be evident from Fig. 4, the additional .resistance member 28 renders possible two trated, in detailv` in Figs. 5a and 11, respectively. The system of operation is otherwise strictly analogous to thatshown in Fig. '1.

The form of my invention shown in Fig. 12 is the same as that shown for Fig. 1 and, in addition, another transformer tap `9 is provided for the intermediate tap. The acceleration is the same as indicated in connection with Fig. 1, the resistance member 25 being employed firstin series relation before operating'as a doubly-fed motor on the tap 3, then being employed as a preventive device in the transition from the tap 3 to the 'tap 5 and finally, being employed .again as a preventive devicein the transition from the tap 5 to 'the tap 9, the destructive transition connection being shown in Fig. 12a.

In the form of my invention shown in Fig. 14what may be termed a sub-,repulsion operation is employed, in that the armature winding is not short circuited as in the ordinary repulsion motor, but is connected to the source so that current is passed therethrough in the opposite direction from -that employed in the ordinary compensated motor as described and claimed in my copending case, Serial No. 33,481, filed June 11, 1915, and assigned to the Westinghouse Electric & Manufacturing Company.' At the outset, .by closing the switches 1, 12,'3 and .6 as shown in F1 14, the armature 22 is connected to the line in a reverse direction from that ordinarily employed, the main field and cross field windings are connected in series relationthrough the resist.- ance member 25, and a minimum Voltage is applied to the main and cross field windings.

.difference between the armature an .plied to the cross field winding is now raised in the ordinary manner. Next, by the ma- 30 nipulation of the switches 12, 4, 5 and 5 and of themember 25, the voltage applied tothe intermediate tap is raised, asindicated in Fig. 1. It will be particularly noted in connection with the system of Fig. 14 that the armature current is maintained at a minimum in starting, by connecting the main and cross field windings in series, the cross field in this type of apparatus beingr provided with twice the number of turns of the armature winding, and, later on,

.when normal operation is attained, the current is increased by connecting the main field winding in series with the armature.

The system of Figi 16 is similar to ,that of Fig. 14 but diders in that the switch 4, controlling the direct connection between the main and cross-field windings is eliminated and, at the outset, the motor windings are all-connected in series rather than with the connections employed in Fig. 14, as shown in Fig. 16a. The remaining operation is similar to that set forth in detail.

In the system of Fig. 18, my invention is shown as applied to a motor of the compen- 105 sated commutator type, wherein, at the outr set, the main eld winding is excited by te 't e cross field exciting currents. On the first accelerating notch, the switches 1, 2, 13 and 6 are closed, short circuiting the 'armature winding through the main field winding-and energizing' the cross field winding with a minimum voltage from the tap 6 through the resistance member 26, as indicated in the accelerating step 1 in Fig. 19 and in Fig. 20. The member 26 is then eliminated by closing the switch 11, as shown in Fig. 21. The initial step toward the setting u of a doubly-fed connection is now taken y introducing a connection from the inner terminal of the cross field winding 24 4to the tap 5, (step 3) (Fig. 22) and the armature and cross field windings are next disconnected by opening the switch 13, (step 4) 125 field winding, the common connection receiving current from the tap through the member 25. rlhe short circuit ofthe main field winding on the armature is now Iremoved (Fig. byV opening the switch 2a and, in the next step, (Fig. 26) the member 25 is eliminated and doubly-fed connectionv is established. From this point on, the acceleration follows the established practice vin that the switches 6, 7 and .8 and the member 27 are manipulated, as shown injsteps 8, 9 and 10, to shift the outer lead of the cross field winding 24 from the tap 6 to the tap 8-to obtain a voltage increase (Fig. 27 ).4

' spirit thereof, and I desire, therefore, that no limitations shall vbe placed thereupoh eX- cept such as are imposed by the prior art or are specifically set forth in the appended claims.

I claimas my invention 1^ i 1. The -combination with a compensated commutator motor, of a control system therefor including an impedance member, means Aparatus whcreb lfor first inserting said member between the .armature and cross eld windings of said motor, and means for thereafter employing said member-as a preventive device in adjusting the voltage supplied to said motor.

. 2. rl`hecombi1uation with a source of alternating current, ofa dynamoelectric inachine of the single-phase commutator type provided with a cross-field winding, and means providing connections from the terminals of said machinev to said source and from an intermediate point of the machine circuitto said source, said means comprising an impedance device and switching apsaid device may, at times, be employed to increase the impedance of the main motor circuit, at other times, may

be short-circuited, and at still other times,

may be repeatedly employed as a bridging member in adjusting thevoltage-supplied to said intermediate connection.

3. ln a control system, the combination with a multi-voltage-tap source'of singlephase current, a compensated Lccmmutator motor adapted to be connected thereto, severable leads-from the armature and main field windings to a pair of source taps, suitable leads from the cross field winding to another pair of source taps, and` an impedance device with a short circuiting device therefor connected betweenv a tap in one pair and atap-inthe other pair.

ln testimony whereof, I have hereunto subscribed my'name this 29th day of May RUDOLF E. HELLMUND. 

